You will lose access to theme/plugin updates and support when your license(s) expires.
Your website will not stop working.
You should renew your license to continue receiving updates, which address compatibility with new versions of WordPress and browsers, contain bug fixes and often include enhancements and new features. Renewal also provides you with an additional year of one on one support.
It is recommended to always run the latest version of WordPress, themes and plugins for stability and security.
Please read License Keys for more information.